In wireless communication systems, a control channel resource set (CORESET) is defined as a set of resource element groups (REGs) within which a user equipment attempts to decode downlink control information. Current standards, as well as standards being developed for fifth generation (5G) access networks, which can also be referred to as New Radio (NR) access networks, define control channel resource sets. A user equipment can have one or more control channel resource sets.
Each control channel resource set is associated with a search space that indicates the set of Control Channel Element (CCE) locations where the user equipment may find the Physical Downlink Control Channels (PDCCHs). The search space includes one or more aggregation levels, defined as the number of control channel elements aggregated for transmission for each PDCCH, and the number of decoding candidates for each aggregation level. The time/frequency resource containing at least one search space is obtained from the management information base (MIB), system information, or is implicitly derived from initial access information. Time/frequency resource containing additional search spaces can be configured using dedicated Radio Resource Control (RRC) signaling.
A search space in NR networks is associated with a single control channel resource set. The search spaces in different control resource sets are defined independently.